Relay actuating saturable inductor



United States Patent 3,182,229 RELAY ACTUATING SATURABLE INDUCTOR Robert E. Wesslund, St. Paul, Minn, assignor to Sperry Rand Corporation, New York, N.Y., a corporation of Delaware Filed Apr. 14, 1961, Ser. No. 103,126 4 Claims. (Cl. 317-448) The present invention relates generally to a relay actuating apparatus and more specifically to such a device consisting of a magnetic core circuit.

In present-day computer art, a considerable use is made of ferromagnetic cores as memory elements, and as logical building blocks. In certain practical applications of such memory elements, it is often required that core circuit output signals be transferred to a bank of solenoids, relays and the like. 'F or example, the peripheral equipment used in the computing system is often of an electromechanical nature in which solenoids are energized to actuate a card punch, an electric typewriter or the like. In the past, the signal output of a magnetic core device has been used to trigger vacuum tubes which, in turn, served to energize such peripheral equipment by actuating a relay or solenoid. However, inherent in the use of vacuum tubes in the circuitry are many disadvantages such as the relatively large size of the electronic package resulting when tubes are used, greater power requirements, and also the possibility of failure of the tubes due to their limited life or breakage.

It is among the objects of the present invention to obviate or minimize the limitations mentioned above by eliminating the use of vacuum tubes. This is accomplished in the present invention by providing a single, saturable inductor functioning not only as a memory cell but also as a self-latching relay or solenoid actuator. Although the change in flux caused by switching a core produces a sizable single voltage pulse across the windings on the core, the output signal is of very short duration. The short output pulse ceases before the relay is latched. The present invention utilizes a capacitance to serve as a delay or energy storage means between the core and the relay for maintaining the output signal over a longer time interval. The present invention also introduces a restore or non-restore feature whereby the signal induced as a result of the collapse of the magnetic field in the relay can be utilized for switching a magnetic core to restore the preexisting magnetic state of the core.

It is, therefore, a principal object of this invention to provide a single, saturable reactor means for storing indicating signals and applying same to an output load.

A further object of the present invention is to provide a saturable reactor, operatively associated with the relay means, such that the relay means may serve to restore or not restore the pre-existing state of the magnetic core.

A further object of this invention is to provide an actuating circuit in which greater reliability is obtained through the employment of saturable core reactors in place of conventional tube-type circuitry.

A still further object of this invention is to provide a means whereby the short output pulse caused in a winding by the switching of a core is delayed by use of passive storage elements for a sufiicient duration of time to cause a conventional relay to latch.

These and other more detailed and specific objectives will be disclosed in the course of the following specificaice tions, reference being had to the accompanying drawings in which:

FIGURE 1 is a graphical representation of a substantially rectangular hysteresis loop of a magnetic material of the type commonly used to make magnetic cores.

FIGURE 2 is a saturable reactor circuit embodying this invention, and serving to actuate a self-latching relay.

FIGURE 1 illustrates a substantially rectangular hysteresis loop developed by plotting the various fiux density conditions (B) of a magnetic material against the applied magnetizing forces =(H). It is commonly known that a variety of magnetic materials exhibit such a hysteresis loop characteristic. Therefore, the core member referred to in the following description may be made from a variety of magnetic materials, among which are 479 Moly-permalloy, and other kinds of ferromagnetic alloys, as long as the material exhibits the hysteresis loop preferably approaching the rectangular form shown by the loop of FIGURE 1. It is also well known that the core may be constructed in a number of geometric forms involving both open and closed paths. It is, therefore, to be understood that the invention is not to be limited by the many variations of material and geometry which will readily suggest themselves to those skilled in the art.

In FIGURE 1 the horizontal axis represents the magnetizing force (H) applied to a magnetic core, while the vertical axis represents the flux density (:B) resulting within the core. +B indicates the state of maximum flux density Within the core when it is substantially saturated in the arbitrarily designated positive direction. +B indicates the remanent flux density and represents a degree or state of flux density to which the core returns when the saturating or magnetizing force H is removed. -13, and B represent states of flux density resulting when the magnetizing force is applied in an opposite or negative direction of magnetization.

If it is assumed that the core is initially in its -B state, a large positive magnetizing force will cause the state of the core to switch to a state of positive saturation, represented by +B When the positive magnetizing force is removed, the magnetization is said to relax to a residual magnetic state identified on the figure as +:B,. The reverse is true if the core is originally in the +l3 state, and a large negative magnetizing force is applied to the core.

Referring now to FIGURE 2 or" the attached drawing, there is shown an embodiment of this invention consisting of a circuit for controlling the actuation of a self-latching relay by means of an output signal from a single, saturable inductor. The core '13 which exhibits a substantially rectangular hysteresis loop is magnetically coupled to three windings, a signal or input winding 26, a power or readout winding 22 and the sense or output winding 24. Pulse generators 7t and '72 connected respectively to the windings and 22 provide current pulses of a predetermined wave form to the windings. The upper terminal 26 of the output winding 24 is serially connected through a diode 28, poled as shown, and over the conductor 32 to one terminal 34 of the relay actuating coil 3%. The other terminal 36 of the relay actuating coil 38 is connected by way of line 46 to the other end of winding 24 at terminal 46. Connected in parallel with the relay actuating coil 38 is energy storage capacitor 3i and a series circuit consisting of the normally open switch 42 and the diode 44.

The relay means 39 includes an actuating coil 38 and relay contacts or switches 52 and 53, which are mechanically coupled to each other. Contact 52 may be termed the holding contact whereas contact 53 is used to control the energization of some external circuit. Conductor 56 connects terminal 54 of switch 52 with the terminal 58 of the normally closed push-button switch 62. The other terminal 6d of the push-button switch is connected by conductor 6t to voltage source 64. Relay contact 51 is electrically connected through conductor 50 and current limiting resistor 48 to terminal 34 of the relay actuating coil 38.

Although FIGURE 2 shows that two pulse generators are used to provide current to the windings Z and 22, it is to be understood that the present invention is not limited to the illustrated embodiment. For example, a single pulse generator supplying bipolar pulses may be used and consequently one or the other of the signal or power windings may be eliminated. The signal pulse generator could be connected to winding 2i? and a positive pulse excursion be made to switch the core in one direction and a negative pulse used to switch the core in the other direction. It may also be noted that voltage source 64 could be a source of negative voltage if diodes 2d and 44 were poled opposite to the manner shown It is obvious to one skilled in the art that a pulse generator may take many forms, such as, a monostable or bistable mulivibrator circuit or a circuit employing magnetic cores. In the latter case, for example, the switching of a magnetic core in a shift register or similar device could be utilized to induce a signal in a winding on the core, and this induced signal could, in turn, serve as a pulse for affecting a magnetic core,such as the one employed in the embodiment illustrated by FIGURE 2.

The operation of the circuit of FIGURE 2 will now I be described. Assume that the initial state of core 13 is established at -B a state of negative remanent magnetization. Inasmuch as the signal or input coil 2% is poled oppositely to the power or readout winding 22, a'

pulse of current flowing in the input winding 20, which may arbitrarily be said to represent a binary 1, causes the magnetic state of the core to change from -18,- to +13 and a subsequent pulse of current of the same polarity energizing the power winding 22 reswitches the state of the core from +B to B When an input pulse sets the magnetization of the core in the +B or its arbitrarily defined 1 state, a substantial change in flux is produced and an is induced in the output winding 24. However, the current resulting from this induced in the output winding is blocked by the diode 2.8 when the diode is poled as illustrated, and hence no energy is supplied to the capacitor 30 or relay 3%. The core remains in the +B or 1 state until a pulse is applied to the core winding 22, at which time the core reswitches to the B, or 0 state. The then induced in the output winding 24 is of a proper polarity to cause current to flow in the forward direction of the diode 28 to charge the capacitor 3% very rapidly. For example, in one embodiment this current pulse was several hundred milliamperes in ampli tude, and lasted for only about 100 microseconds.

When the output pulse ceases and the capacitor begins to discharge, diode 28 prevents the discharge current from flowing back through the winding 24. Therefore, the discharge current forms a path from the positive ter minal of the capacitor through the conductor 32, through the relay actuating coil 38, and throughthe conductor 4% back to the negative terminal of the capacitor. The impedance of the relay actuating coil 38 retards the flow of the discharge current so that the capacitor 3% discharges over a period-of timedependent on the RC time constant of the just traced circuit path. One skilledin 1 the art will realize the time constant desired'is relative to the reaction time of the associated relay, and thus the current may flow for several milliseconds.

Once the relay armature 52 is closed, the relay means 39 becomes self-latching because of the current supplied 7 to the relay actuating coil'38 by the voltage source 64.

The circuit is now traced as being from source 64 through conductor 63, the normally closed pushbutton switch 62, the conductor 56, the armature 52 of relay means 39, and the current limiting resistor 48 to terminal 34, which is connected to relay actuating coil 38 and thence to ground. The self-latching relay 39 will remain closed until the circuit is opened by opening switch 62. Since switch contact 53 is mechanically coupled to switch contact 52., it will close on contact 66 when the magnetic field induced by current flowing through relay coil 38 causes armature 52 to latch. As mentioned hereinbefore, the circuit completed by the latching of armature 53 may serve to provide a signal indication to a utilization device 67.

In one application, push-button switch 62 or its equivalent can be energized by command signals from the device 67. A command signal could serve to cause switch 62 to open, thus indicating that the information carried by the relay has been sensed by the utilization device. The opening of switch 62 would cause relay 39 to open causing it to assume a ready state for subsequent signals generated in the aforementioned manner by the switching of core in.

Returning now to the construction of the circuit shown in FIGURE 2, it will be further seen that the diode 44 serially associated with switch 42 is connected across the relay, to be restored if desired. With switch .2 a

closed, the energy stored in the magnetic field of the relay, which is released in the form of current when the relay is unlatched by opening switch 62, is dissipated in a circuit including the diode 44, and very little energy reaches the output winding 24 of the core. With switch 42 opened, however, the current resulting from the collapse of the magnetic field of the relay actuating coil 38 now flows through the conductor 40, winding 24, and through line 32 to terminal 34 of the relay coil 38. This current is initially of sufiicient amplitude and flows in the output winding 24 ina direction to'cause the core to reswitch, thus restoring it to its pre-existing state.

In the sense then, that energy initially supplied by the switching of the core is used to restore the core to its pie-existing state, it may be said that the readout is nondestructive.

It is understood that suitable modifications may be made in the structure as disclosed provided such modifications come within the spirit and scope of the appended claims.

Having now, therefore, fully illustrated and described.

my invention, what I claim to'be new and desire to protect by Letters Patent is:

1. In a relay actuating circuit, the combination comprising: a magnetic core having substantially rectangular hysteresis loop characteristics, and having at least two windings coupled thereto; a source of bipolar pulses connected to a first of said windings for initially setting said core in a first remanent magnetic state, and for subsequently driving said core to its opposite magnetic state to induce substantial signals in a second of said windings; relay coil means having first and second terminals and at least one set of contacts associated therewith; energy storage means connected across the first and second terminals for storing said signals in a first interval of time,

means connecting the other of said set of contacts to said 7 first terminal, such that said energy supplied by said storf age meansinitially causes said contacts and said voltage source maintains saidcontacts in a closed condition;

' means toettect an opening of said contacts; means connecting said terminals in series circuit with said second winding for allowing the signal induced by the collapse References Cited by the Examiner UNITED STATES PATENTS Sunstein 317-151 Trousdale 317-1485 Myers 317-1485 Hoffman 317-1485 Olson et a1 317-148 X Chen et a1. 328-40 SAMUEL BERNSTEIN, Primary Examiner. 

1. IN A RELAY ACTUATING CIRCUIT, THE COMBINATION COMPRISING: A MAGNETIC CORE HAVING SUBSTANTIALLY RECTANGULAR HYSTERESIS LOOP CHARACTERISTICS, AND HAVING AT LEAST TOW WINDINGS COUPLED THERETO; A SOURCE OF BIPOLAR PULSES CONNECTED TO A FIRST OF SAID WINDINGS FOR INITIALLY SETTING SAID CORE IN A FIRST REMANENT MAGNETIC STATE, AND FOR SUBSEQUENTLY DRIVING SAID CORE TO ITS OPPOSITE MAGNETIC STATE TO INDUCE SUBSTANTIALLY SIGNALS IN A SECOND OF SAID WINDINGS; RELAY COIL MEANS HAVING FIRST AND SECOND TERMINALS AND AT LEAST ONE SET OF CONTACTS ASSOCIATED THEREWITH; ENERGY STORAGE MEANS CONNECTED ACROSS THE FIRST AND SECOND TERMINALS FOR STORING SAID SIGNALS IN A FIRST INTERVAL OF TIEM, AND FOR SUPPLYING ENERGY TO SAID RELAY MEANS FOR A SECOND INTERVAL OF TIME GREATER THAN SAID FIRST INTERVAL; A VOLTAGE SOURCE CONNECTED TO ONE OF SAID SET OF CONTACTS; MEANS CONNECTING THE OTHER OF SAID SET OF CONTACTS TO SAID FIRST TERMINAL, SUCH THAT SAID ENERGY SUPPLIED BY SAID STORAGE MEANS INITIALLY CAUSES SAID CONTACTS AND SAID VOLTAGE SOURCE MAINTAINS SAID CONTACTS IN A CLOSED CONDITION; MEANS TO EFFECT AN OPENING OF SAID CONTACTS; MEANS CONNECTING SAID TERMINALS IN SERIES CIRCUIT WITH SAID SECOND WINDING FOR ALLOWING THE SIGNAL INDUCED BY THE COLLAPSE OF THE MAGNETIC FIELD IN THE RELAY TO RE-ESTABLISH THE PREEXISTING REMANENT STATE OF SAID CORE. 